[Pellet-users] Internal Triple Representation of owl:unionOf (a b) as rdf:List

[Wolfgang May]

Hi,

constructs like 
 :Person a owl:Class; owl:unionOf (:Male :Female).
are translated to collections/rdf:List constructs.
Although, pellet seems not to "know" that this these things are
rdf:Lists:

***
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix owl: <http://www.w3.org/2002/07/owl#>.
@prefix : <foo://bla/>.

:Male a owl:Class.
:Female a owl:Class.

:Person a owl:Class; owl:unionOf (:Male :Female).
:EqToPerson a owl:Class;
  owl:unionOf 
  [ a rdf:List; rdf:first :Male;
    rdf:rest [ a rdf:List; rdf:first :Female; rdf:rest rdf:nil]].
:x a :Person.
***

***
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix owl: <http://www.w3.org/2002/07/owl#>
prefix : <foo://bla/>
select ?X ?Y ?Z
from <file:union-list.n3>
where {?X rdf:first ?Y . OPTIONAL {?X rdf:rest ?Z}}
***

results -as expected- in

--------------------------------------------------------------------------------
| X    | Y                  | Z                                                
================================================================================
| _:b0 | <foo://bla/Male>   | _:b1                                             
| _:b2 | <foo://bla/Male>   | _:b3                                             
| _:b3 | <foo://bla/Female> | <http://www.w3.org/1999/02/22-rdf-syntax-ns#nil> |
| _:b1 | <foo://bla/Female> | <http://www.w3.org/1999/02/22-rdf-syntax-ns#nil> |
--------------------------------------------------------------------------------
Successfully printed 4 query results.

But, if I ask whether ?X is a list, the answer to

***
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix owl: <http://www.w3.org/2002/07/owl#>
prefix : <foo://bla/>
select ?X ?Y ?Z
from <file:union-list.n3>
where {?X a rdf:List; rdf:first ?Y . OPTIONAL {?X rdf:rest ?Z}}
***

is only

--------------------------------------------------------------------------------
| X    | Y                  | Z                                                
================================================================================
| _:b0 | <foo://bla/Female> | <http://www.w3.org/1999/02/22-rdf-syntax-ns#nil> |
| _:b1 | <foo://bla/Male>   | _:b0                                             
--------------------------------------------------------------------------------
Successfully printed 2 query results.

 
Obviously, for 
  owl:unionOf (...) 
the list *structure* is generated, but rdf:type rdf:List
is not assigned.

Is there a reason for this (from a previous post, I already learnt
that rdf:first and rdf:rest cannot be used for reasoning)? It would
be nice for some applications (e.g. analysis of ontologies) to
have access to these properties for querying and processing 
collection-based concept definitions.

Best,
Wolfgang